1. Field
One or more embodiments of the present invention relate to a method and apparatus for detecting a defect of a barrier film.
2. Description of the Related Art
A known method of measuring a moisture intrusion rate with respect to a barrier film is by using a calcium (Ca) electrode. When a Ca electrode is wrapped with a test barrier film and exposed in an environment of moisture and oxygen, the moisture and oxygen reacting with the Ca electrode may be detected by an optical or electrical measurement apparatus. In doing so, a special pad equipped with a Ca film is used, however, such a special pad may not be applied to a flat panel display device such as an organic light emitting diode (OLED) display. Also, because this measurement method is available only after moisture or oxygen has intruded into a barrier film due to a defect of the barrier film, it is not possible to detect existence of a defect using Ca electrodes before the intrusion of moisture or oxygen. When a display device is placed in a high moisture environment for long time due to this measurement, even if a barrier film is determined to have no defect, lifespan of the flat panel display device may be deteriorated.
U.S. Pat. No. 5,196,799 discloses that even a very small hole may be critical to a film intrusion rate.